Department of Ecology

The importance of birds as natural control agents of white grubs in grassland systems

K. Schallhart, C. Wallinger, A. Juen (PI), M. Traugott (PI)

Besides invertebrate predators and entomopathogenes, birds may significantly contribute to regulate scarab larvae populations. It is assumed that avian predation, especially predation by carrion crows (Corvus corone corone), can help to regulate scarab populations in grassland ecosystems. To test this hypothesis, exclusion experiments in an alpine meadow have been set up. These will enable us to determine the impact of crow predation on the population density of scarabs, the vegetation, and grass yield. To record the activity and small-scale distribution patterns of the birds, a special camera system, automatically taking pictures at defined time intervals, will be used. In addition, we evaluate the environmental conditions which affect the crows’ density and activity patterns. By conducting a cost-benefit analysis the advantages of bird predation will be compared to the damages crows can potentially cause when feeding on grubs. This will allow evaluating the birds’ impacts on pests, the vegetation, and yield in a practical way.